A mission critical push to talk (MCPTT for short) over service is a service based on a 3GPP evolved packet system (EPS for short), and may be applied to public safety and business scenarios. The MCPTT service may support communication of multiple MCPTT users (that is, a group call), where each MCPTT user can obtain the floor by means of arbitration.
In the conventional art, MCPTT users are configured to belong to a preset MCPTT group, for example, policemen or firefighting force. Then, the MCPTT users perform group communication in the preset MCPTT group, so as to better coordinate with each other to complete a task. However, an MCPTT user cannot choose to associate with an MCPTT group that the MCPTT user is interested in.